Fair Value Measurements (Narrative) (Details) (USD $)	6 Months Ended
	Jun. 30, 2013	Mar. 31, 2013	Dec. 30, 2012	Jul. 01, 2012	Apr. 01, 2012	Jan. 01, 2012	Jun. 30, 2013 2015 Notes [Member]	Dec. 30, 2012 2015 Notes [Member]	May 30, 2008 2015 Notes [Member]	Jun. 30, 2013 2021 Notes [Member]	Dec. 30, 2012 2021 Notes [Member]	Oct. 25, 2011 2021 Notes [Member]	Jun. 30, 2013 Financing Lease Obligations [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliations, Recurring Basis, Liability Value	$ 3,715,000	$ 2,727,000	$ 3,017,000	$ 7,315,000	$ 20,636,000	$ 20,298,000
Business Combination, Contingent Consideration Arrangements, Description	Contingent consideration is measured at fair value at the acquisition date, based on the probability that revenue thresholds or product development milestones will be achieved during the earnout period. The earnout periods for each of these acquisitions do not exceed three years from the acquisition date.
Business Acquisition, Contingent Consideration, Potential Cash Payment	36,800,000
Business Combination, Contingent Consideration Arrangements, Maximum Period	3 years
Unsecured revolving credit facility, amount	700,000,000
Unsecured senior notes, face value							150,000,000		150,000,000	500,000,000		500,000,000
Revolving credit facility outstanding balance	316,000,000		258,000,000
Unsecured senior notes, carrying value							150,000,000	150,000,000		497,300,000	497,200,000
Debt Instrument, Unamortized Discount										2,700,000	2,800,000	3,100,000
Unsecured senior notes, fair value							$ 160,900,000	$ 165,400,000		$ 533,100,000	$ 558,300,000		$ 40,800,000